Everything You Need to Know about Narcissists, Psychopaths, and Abuse - click on this link: http://www.narcissistic-abuse.com/faq1.
Why do some narcissists appear to be bumbling fools, never mind how intelligent they actually are? Eight reasons:
1. No impulse control, no forethought, no foresight = counterproductive, self-defeating, and self-destructive decisions and actions.
2. Acting out: when narcissistic supply is deficient, narcissists decompensate and go haywire (see: http://samvak.tripod.com/journal42.html and my post on collapsed narcissists).
3. Pseudo-stupidity: to avoid the consequences of their misdeeds, narcissists pretend that they have misunderstood something you have said or done or that you took advantage of their good nature.
4. Gullibility: narcissists are grandiose and fantasts, so they misjudge reality (impaired reality test), their skills and limitations, and the intentions of others.
5. No empathy means that the narcissist disastrously misreads others and behaves in socially unacceptable and clownish ways.
6. His sense of entitlement renders the narcissist an overweening buffoon, the butt of mockery and derision, rather than the awe he believes that he inspires and the respect he thinks that he deserves.
7. Hypervigilance leads to disproportionate aggression directed at imaginary slights and to persecutory delusions: paranoid ideation often directed at innocent targets.
8. Finally, the narcissist uses false modesty to fish for compliments. But his attempts are so transparent and inarticulate, so fake and manipulative that people react with repulsion and seek to humiliate him. The narcissist regards learning something new and getting advice as narcissistic injuries because both situations imply that he is not perfect and not omniscient (all-knowing).
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)